Rear wheel drive vehicles which are selectively engageable to be four wheel drive vehicles have a transfer case. The transfer case typically has a primary shaft which is connected to the output of a vehicle transmission. The primary shaft typically rotatably mounts a sprocket that engages a chain. The chain typically engages with another sprocket that is typically connected with a secondary shaft. The secondary shaft is rotatably mounted within the transfer case. The secondary shaft is torsionally connected with a front drive shaft that is torsionally connected with a front differential to power front wheels of the vehicle. To provide a function of selectively engaging the front wheels of the vehicle, there is provided a clutch mechanism that selectively engages the sprocket on the primary shaft with the primary shaft to transfer torque from the primary shaft to the secondary shaft thereby selectively engaging the front wheels of the vehicle. When ideal pavement conditions exist, typically the clutch not be engaged so that the transmission only torsionally engages the rear wheels of the vehicle. A controller is typically provided which is cognizant of wheel slip conditions to automatically control the engagement of the clutch. In some four wheel drive embodiments, the clutch can also be engaged as a result of operator demand.
Most transfer cases in normally rear wheel drive vehicles with longitudinally mounted engines have a portion of the transfer case housing connected to a rear of the transmission housing. Typically the transfer case housing also has a yoke. The yoke typically has a polymeric isolator inserted therein that is fastener connected to a crossbar member of the vehicle chassis. To meet fuel economy standards in the last 3 decades there's been a constant quest to reduce vehicle weight. Accordingly most transfer case housings are fabricated from aluminum. For a cost standpoint, most housing are fabricated using a casting process. However in a vehicle crash situation is desirable for the transfer case to be resistant as possible to deformation so that the vehicle's drivetrain is functional after a crash. It is desirable to retain the use of aluminum transfer case housing, while at the same time providing a transfer case housing having enhancement strength capabilities in automotive crash situations.